KMS capture: "Couldn't find [/dev/dri/card2]: This shouldn't have happened :/" on multi-GPU (NVIDIA dGPU + AMD iGPU) when only iGPU has an active output

[fisherjoey]

Is there an existing issue for this?

• I have searched the existing issues (closest: KMS capture fails with 0x3003 RGB import error on multi-GPU #4940 and Error: Couldn't import RGB Image: 00003003, on RTX 5090 using NVENC, alongside other GPUs using Wayland (Ubuntu/Fedora), giving a black screen. #3778, but both describe a downstream 0x3003 RGB import error on dual-NVIDIA setups — that's a different failure later in the capture pipeline than this)

Is your issue described in the documentation?

• I have read the documentation

Is your issue present in the latest beta/pre-release?

Not tested on the latest pre-release. Present on 2025.924.154138 (commit 86188d47a7463b0f73b35de18a628353adeaa20e) from the Fedora Copr build shipped by Nobara. Code path looks identical in main.

Describe the Bug

On a multi-GPU system (NVIDIA dGPU on card1, AMD iGPU on card2), when all outputs on the primary DRM card are disabled and only an active output exists on the secondary card, Sunshine's KMS capture consistently fails with the error:

Found monitor for DRM screencasting
Error: Couldn't find ["/dev/dri/card2"]: This shouldn't have happened :/

…repeated for every encoder probe (nvenc, vaapi, software), ending in:

Fatal: Unable to find display or encoder during startup.
Fatal: Please check that a display is connected and powered on.

Wayland output enumeration does succeed — Sunshine logs the wl_output interface version for the monitor on card2 and even reports Found monitor for DRM screencasting. It's the very next step (opening /dev/dri/card2 for KMS capture) that bails with the internal "This shouldn't have happened" error.

The moment I re-enable any output on card1, Sunshine captures that one fine. Capture on card1 has always worked in my setup. The failure is specific to capturing from a non-primary DRM card when the primary has no active outputs.

Full log excerpt

[2026-04-23 20:37:35.870]: Info: /dev/dri/card1 -> nvidia-drm
[2026-04-23 20:37:35.870]: Info: /dev/dri/card2 -> amdgpu
[2026-04-23 20:37:35.870]: Info: Found monitor for DRM screencasting
[2026-04-23 20:37:35.870]: Error: Couldn't find ["/dev/dri/card2"]: This shouldn't have happened :/
[2026-04-23 20:37:36.071]: Info: Screencasting with KMS
[2026-04-23 20:37:36.071]: Info: /dev/dri/card1 -> nvidia-drm
[2026-04-23 20:37:36.071]: Info: /dev/dri/card2 -> amdgpu
[2026-04-23 20:37:36.071]: Info: Found monitor for DRM screencasting
[2026-04-23 20:37:36.071]: Error: Couldn't find ["/dev/dri/card2"]: This shouldn't have happened :/
...
[2026-04-23 20:37:36.676]: Info: Encoder [software] failed
[2026-04-23 20:37:36.676]: Fatal: Unable to find display or encoder during startup.
[2026-04-23 20:37:36.676]: Fatal: Please check that a display is connected and powered on.

Expected Behavior

Sunshine should capture the active monitor on card2 (amdgpu) regardless of whether card1 (nvidia) has any active outputs. At minimum, the "This shouldn't have happened" code path should produce an actionable error instead of an internal-state assertion.

Steps to Reproduce

1. Multi-GPU Linux system: NVIDIA dGPU (card1) + AMD iGPU (card2). KDE Plasma 6 on Wayland.
2. Create a virtual display on card2 via kernel EDID injection (to have something to capture without physical hardware):
   • Put a valid 2560×1600 EDID at /lib/firmware/edid/macbook-virtual.bin
   • Kernel cmdline: drm.edid_firmware=DP-1:edid/macbook-virtual.bin video=DP-1:e
3. Boot. Confirm /sys/class/drm/card2-DP-1/status = connected, enabled.
4. kscreen-doctor output.DP-1.enable output.DP-1.mode.2560x1600@60 output.HDMI-A-3.disable output.DP-5.disable (disable everything on card1, leave only card2-DP-1 active).
5. Connect a Moonlight client and launch any Sunshine app. Capture fails as above.

Re-enabling any output on card1 (kscreen-doctor output.HDMI-A-3.enable ...) makes Sunshine capture it successfully — confirming the failure is about the non-primary DRM card path, not the virtual display itself.

Additional Context

Use case: trying to use a kernel-injected virtual DP on the iGPU as a headless display target for streaming, so that neither the OLED nor TV physically lights up during MacBook/iPad streaming sessions. The kernel and KDE handle this cleanly — kscreen-doctor shows DP-1 as connected enabled 2560x1600 scale 2.0, and Sunshine's Wayland enumeration sees it. Only the KMS capture path is blocked.

Possibly related but distinct:

• KMS capture fails with 0x3003 RGB import error on multi-GPU #4940 — multi-GPU dual NVIDIA, 0x3003 RGB import error — that's failing later (during DMA-BUF cross-GPU import). Our error is earlier: Sunshine can't even proceed from "Found monitor" to opening the card device.
• Error: Couldn't import RGB Image: 00003003, on RTX 5090 using NVENC, alongside other GPUs using Wayland (Ubuntu/Fedora), giving a black screen. #3778 — similar 0x3003, closed.
• global_prep_cmd do scripts run after encoder probing, breaking virtual display setups #4971 — prep-cmd timing with virtual displays (fixed, separate issue).

Host Operating System

Linux

Operating System Version

Nobara 43 (Fedora 43 base). Kernel 6.19.11-201.nobara.fc43.x86_64. KDE Plasma 6.6.2, KWin 6.6.2 on Wayland.

Architecture

amd64/x86_64

Package

Linux - Fedora Copr

GPU Type

AMD

GPU Model

Multi-GPU:

• card1 (primary): NVIDIA GeForce RTX 3070 Ti (GA104), PCIe 01:00.0
• card2 (secondary / iGPU): AMD Ryzen 7000 Raphael integrated, PCIe 10:00.0

GPU Driver/Mesa Version

• NVIDIA: 595.58.03 (open kernel module)
• AMD: Mesa 26.0.4 (amdgpu)

Capture Method

KMS (Linux)

[fuomag9]

Same issue for me, I'm also using a kernel injected DP. This started happening overnight on bazzite :(